Breast Cancer: Marine Omega-3s More Effective Than Plant-Based Omega-3s in Lab Animals in Fighting the Disease

Omega-3s may have a preventive effect on breast cancer, particularly EPA and DHA found in fish, which appear to be eight times more effective at inhibiting tumor development and growth compared to those found in plant-based foods such as flax seeds. A recent study conducted on laboratory mice demonstrated that consuming marine-derived omega-3s reduces the number of tumors by 30% and their size by 60-70%, while higher doses of plant-based omega-3s are needed to achieve the same effect.

The protective role of omega-3s in breast cancer onset 

Breast cancer is the most common cancer among women worldwide, accounting for 29% of all cancers affecting females. In Italy, it is the most frequent neoplasm, affecting one in eight women over their lifetime, with 53,200 new cases reported in 2018 alone.

According to numerous studies there is a link between breast cancer onset and poor dietary habits.

Moreover, increasing scientific evidence highlights the importance of a healthy diet in disease prevention and recurrence reduction.

In particular, fatty acids seem to play a role in the risk of this cancer. Supporting this, epidemiological studies have found significant differences in disease incidence between populations following Asian versus Western diets.

Asian diets typically include high fish consumption, which is rich in omega-3 fatty acids and is associated with a lower incidence of breast cancer compared to populations consuming typical Western foods.

However, omega-3s are not found only in fish; they can also be obtained from plant sources. Alpha-linolenic acid (ALA), for example, is found in edible seeds like flaxseed and oils such as soybean, canola, and hemp, while EPA and DHA are primarily marine-derived and present in fish, algae, and phytoplankton.

Although several studies have associated omega-3 intake with reduced breast cancer risk, the majority of evidence and the specific mechanisms responsible for protective effects remain inconclusive.

Marine-derived omega-3s are more effective than plant-based ones

Canadian researchers, led by Professor David Ma, investigated the role of omega-3s from different sources in breast cancer development using animal models, studying the effects of diets enriched with different omega-3 types on mice with a highly aggressive form of human breast carcinoma called HER-2, which affects 25% of women and has a poor prognosis.

It is known that EPA and DHA can inhibit breast tumor growth, but no direct comparison of the efficacy of these omega-3s versus ALA had been made before.

The research results revealed that marine-based omega-3s are eight times more effective at inhibiting tumor development and growth; although plant-based omega-3s also seem to counter the tumor, a higher dose is required.

"This study is the first to compare the potency of plant-based omega-3s to marine-derived ones on breast cancer development," said Professor Ma. "There is evidence that both plant and marine omega-3s are protective against cancer, and we wanted to determine which form is more effective," he continued.

A unique aspect of the study was that mice were "exposed" to the different omega-3 types in utero, before tumors developed, allowing the researchers to compare the fatty acids’ role in disease prevention.

Emerging research suggests that early exposure to omega-3s during the critical period when the mammary gland undergoes remodeling may alter susceptibility to cancer later in life.

EPA, DHA, and ALA have been shown in previous studies to prevent and combat cancer by activating immune system genes that block tumor growth pathways.

According to the researchers, omega-3s may also help fight other types of cancer, and it is advisable to consume two to three servings of fatty fish per week to maximize omega-3 intake.

Some details on the discovery process

To conduct the study, researchers used normal mice and mice with mutations responsible for mammary tumors.

The animals were divided into 4 groups and randomly assigned diets enriched with the following oils: safflower oil, flaxseed oil (at 3% and 10%), and fish oil. All diets were isocaloric, with 20% kcal from protein, 58% kcal from carbohydrates, and 22% kcal from fat.

The flaxseed oil diets at 3% and 10% contained varying levels of ALA and were used to test the dose-response relationship between plant-based omega-3 exposure and tumor onset.

Results showed that lifelong exposure to omega-3s from either plant or marine sources can delay mammary tumor onset and improve cancer outcomes. They also revealed dose-dependent effects of plant-based fatty acids containing ALA, especially at the higher 10% dose.

The tumor inhibitory effect of ALA was found to be about eight times less potent than that of marine-derived EPA and DHA.

The first recommendation? Increase fish consumption

According to the researchers, the results show that plant-based omega-3 forms have the same impact as fish sources but require higher doses. The recommendation, therefore, is to increase fish consumption, especially among Western populations that follow diets high in saturated fatty acids.

According to Dr. Ma, the significant positive effects omega-3s can have in combating a highly aggressive form of breast cancer suggest that omega-3s are likely useful in fighting other malignancies, and further research in this field will be necessary.

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Source: Liu et al. "Marine fish oil is more potent than plant-based n-3 polyunsaturated fatty acids in the prevention of mammary tumors" The Journal of Nutritional Biochemistry, 2018, Pages 41-52.